DDP Explained: Why It Matters for Aircraft Equipment Installation
When integrating aeronautical equipment into an aircraft, one of the key documents required by a Design Organisation Approval (DOA) is the Declaration of Design and Performance (DDP). Despite its importance, many customers and equipment buyers are unfamiliar with what a DDP is, what it contains, and why it is crucial for installation and certification.
This article explains the purpose of the DDP, what information it contains, and why it is a necessary part of aircraft modification projects under EASA, UK CAA, and FAA regulations.
What is a DDP?
A Declaration of Design and Performance (DDP) is a formal document issued by an equipment manufacturer that provides a summary of the design, performance, and compliance of an aviation component. It is particularly important for installing and certifying equipment on an aircraft, as it declares the extent of qualification and compliance with applicable standards.
For example, an aircraft seat manufacturer will issue a DDP referencing ETSO-C127c, which is the Minimum Performance Standard (MPS) for seats. The DDP ensures that the seat meets the required safety and performance criteria before it can be installed.
What Information Does a DDP Contain?
A typical DDP includes the following key elements. Note that this is a condensed summary of the elements, a full list and template for the DDP is in Part-21.A.608.
1. Compliance with a Minimum Performance Standard (MPS) and the qualified performance level
The DDP states which ETSO (European Technical Standard Order), TSO (FAA Technical Standard Order), or other relevant certification basis the equipment complies with.
2. Environmental Qualification
Equipment must be tested for various environmental conditions per RTCA DO-160 (Environmental Conditions and Test Procedures for Airborne Equipment).
The DDP details the environmental categories for which the equipment has been qualified, such as elements from RTCA DO-160 testing which may include tests for:
- Temperature and altitude
- Vibration and shock resistance
- RF and lightning immunity
3. Limitations or Functions Not Covered by the MPS
Some equipment may include additional limitations, or capabilities beyond those covered by the ETSO/TSO. The DDP will clarify what is certified and what is not, and the rated performance level.
4. Deviations from the MPS
In some cases, equipment may have non-compliances or design deviations from the standard. These must be declared in the DDP.
For example, if a piece of electrical or avionics equipment is not tested for or fails a particular test in DO-160, the DDP will indicate the deviation. Note that the full test-suite typically does not need to be covered, and the installer (i.e. the DOA) will need to assess and justify the component with its DDP-declared performance level and qualification is suitable as-is for installation. If it is not, the DOA will have to potentially test these missing elements before approval for installation.
5. Document references
The DDP will reference the following types of documents:
- Master drawing record internal to the equipment manufacturer
- Test plans and reports, such as those referencing static/dynamic tests and flammability tests for seats.
- Component Maintenance Manual (CMM) and other relevant manuals for Instructions of Continued Airworthiness (ICA).
- Installation Instructions and Limitations (IIL).
The DDP, ICA, and IIL are typically required by DOAs for installation and approval.
Why is the DDP Important for Aircraft Modifications?
For owners, operators, and buyers of aircraft equipment, obtaining the DDP package is crucial when procuring components for installation by a DOA. Without a DDP, installation can face delays due to missing compliance data, regulatory issues requiring additional approvals, and increased costs if reverse engineering or re-qualification is needed. Some tests (e.g., static or deformation tests) are destructive, making compliance verification by re-qualification impossible due to part shortages in retro-fit cases.
How a DOA Uses the DDP
A DOA relies on the DDP to:
- Verify Installation Feasibility: Ensuring that the equipment can be safely and legally installed in a specific aircraft type.
- Demonstrate Compliance: Proving that the equipment meets the necessary airworthiness and safety standards.
- Support Certification Documentation: Providing necessary compliance data for minor changes, major modifications, or STCs (Supplemental Type Certificates).
Key Takeaways for Equipment Buyers
- When purchasing aeronautical equipment, always request the DDP, manuals, ICA and IIL from the supplier. Without these documents, installation is typically not possible.
- Ensure the DDP covers the relevant ETSO/TSO and, if required, DO-160 qualifications needed for installation. For example, seats must be qualified for the minimum pitch they will be installed at.
- Engage with a DOA early in the process to verify that the equipment meets all airworthiness standards and that the necessary documentation is available.
By understanding and obtaining the DDP early, you ensure a smoother installation, compliance, and certification process, ultimately saving time and costs in your aircraft modification project.
